It's better if you find the root cause y are u getting these security warnings while opening the Oracle form,
This can be achieved by enabling debug option through your Java Console

Start-> Control Panel -> Java ->Advanced
Open 'Java console' and select 'Show console'
Open 'Debugging' and select all 3 options,click OK
Start a fresh browser session and log in to Applications
Start the function calling the Form reproducing the problem
See that Java Console is also started and logs debug entries.

Here you will come to know y ur getting these security warnings.

As a work around.
Start > Control Panel > Java> 'Advanced'
Open 'Security' and 'Mixed code (sandbox vs. trusted) security verification'
Select 'Enable - hide warning and run with protections'
Select OK button to confirm the changes made

Follow the metalink note
How to diagnose and resolve "Java has discovered application components that could indicate a security concern" in Forms [ID 1120573.1]

Have you tried the work around which i have mentioned on my previous post??

Java console is showing is lots of entries but i am unable to understand them.
Can you please post the last few lines from the Java console when you got Java Runtime Security Warnings while your opening the form.

When I run the form that has subclass of webutil.olb It takes extra time in loading form when I enabled the debugging of Java then i found the following entries.
I think form is taking time at last line of following entries.

When form is loaded then following line appear in Java console.
cache: Reading Signers from 978 http://10.0.0.10:8889/forms/java/frmwebutil.jar | C:\Documents and Settings\abc\Application Data\Sun\Java\Deployment\cache\6.0\21\3cfcc115-469e42dd.idx